Process for the chemical retting of lengths of vegetable textiles



United States Patent PROCESS FOR THE CHEMICAL RETTING on LENGTHS or vEoETaB E TEXTILES Claims priority, application France December 27;, 195i] 9 Claims. (Cl. 92 1- -13) This invention relates to an improved process for the chemical retting of lengths of vegetable textiles such as ramie, flax, hemp, jute, urena, ambary, asclepia's or the like.

Chemical retting has the object of solubilising or emulsifying the hemicelluloses, the lignines and the pectic substances which constitute the mean lamina and the agglomerates between the cellulosic clusters of the vegetable mass for the purpose of obtaining a cellulosic-fibr'e freed from the foreign substances and suitable for spinning.

This result may be obtained by means of an alkali base, a neutral salt or a detergent product. This treatment may also be preceded by an acid treatment or oxidation by which depolymerisation is effected and the. decomposition of these incrustingsubstances is facilitated;

Many processes based on the use of the aforesaid chemical agents in various combinations have been proposed. All these processes free the fibre from the greater part of the ligneous materials by which it isc'oatedg" they give a tow of more or less high quality which has a considerable influence on the final properties of the yarn obtained. s

Although it is very difficult' to define thep'roperties of a fibre by numerical data, it is nevertheless true that a specialist can form a fairly accurate idea of the suitability of the fibre for spinning by simple examination and from the feel of the fibre.

It is proposed in accordance with the invention to obtain a material which fully meets allfthe-requireme'nts arising in spinning, namely a fine, strong, white'tow' which is free of oxy-cellulose, e

The invention is based on the following considerations.

The most active chemical substanceforthe decomposition of the substances foreign to thecellulosicfibre is an alkali base such as soda or potash, which-has-the effect of dissolving the pectic substances, the hemicelluloses and the lignine of which the greater part-ofthe products to be eliminated consist. By reasonof its effective corrosive action, it also attacks the cellulose and'degrades it and consequently denatures the fibreswhich it is desired to obtain. It is possible to limit the action of thealkali base to the ligneous and hemicellulosic constituents which it is desired to eliminate, these constituents being less complex than the cellulose and being the first to be attacked. For this purpose, it is desirable to reduce the concentration of the base, which then loses some of its effect and its rapidity of action. It is therefore necessary tosadd thereto an adjuvant which enhances its lignolastic, pe'ctinolytic and hemicellulolytic qualities, i. e. its ability to degrade the ligneous and hemicellulosic substances without attacking the cellulose of the fibres.

The emulsifying products are particularly suitable for this purpose because they perform a double functioini. e. they eliminate the lipides coating the materials foreign to the fibre rendering them water-repellent,1and on the other hand they'facilitate the dispersion 'ofthese substances, which are in the form of colloids ditficult to attack by the alkali solution alone. *Itis known, infact,

that uronic acids, which are the products of decomposition of the hemicelluloses by the bases, are naturally soluble in water provided that they are free from lipides and that the water is pure and heated to a temperature higher than its boilingpoint under formal pressure.

Since the industrial water is not pure and an operating temperature lower than C. is employed, it is necessary, in order to solubilise these incrustations on the fibre, to facilitate the dispersion of the colloids by which they are formed, so that the alkali base can effectively attack them.

In accordance with the invention, it has been found that the most active emulsifier is a palmitate having an amine base. The latter substance combines the properties of its anion (palmitic acid) and of its cation (amine base), both of which arehighly active.

It is to be noted that palmitic acid, as the anion of the emulsifier, gives results clearly superior to those given by its homologues, the other fatty acids such as the oleic acids, the stearic acids, or the like whether sulphonated or not.

-As active cation, the amine bases, whether primary, secondary or tertiary, or in the form of a quaternary ammonium base, are particularly suitable. Thus, morpholine, propanoiamine, tetramethylammonium hydrate, or the like, which are primary, and secondary amines and a quaternary ammonium base respectively, may be cited.

In addition to the depolymerizing action of the soda on the hemicelluloses and the ligneous materials by which they are degraded into less complex products, whereby their elimination by Water is facilitated, it is desirable to treat the lengths of vegetable textiles by an oxidizing agent which exert a depolymerizing action by oxidation and thus completes the action of the soda. The peroxides and the per-salts are particularly well suited for this purpose, in particular hydrogen peroxide, and all the substances by which it is liberated, such as sodium peroxide, the per-salts such as perborates, or the like. Hydrogen peroxide is particularly effective because it is found that thepresence' of an alkali base and of the palmitate of amine base, as emulsifier, greatly promote, the action of the hydrogen peroxide. Moreover, in addition to its depolymerizing action, hydrogen peroxide exerts a bleaching action on the fibres, which is also an object of the retting. The invention has for its object to provide a process for the chemical retting of length of vegetable textiles such as ramie, flax, hemp, jute, urena, ambary, asclepias, or the like, which is distinguished particularly by the fact that it consists in subjecting the said lengths of textiles to a first treatment bymeans of an aqueous solution having an alkali base containing a palmitate of amine base which acts as an emulsifier, and then to a second treatment with an aqueous solution containing the same substances as that employed in the first treatment and containing in addition an oxidizing agent.

The process is carried out in a particularly simple manner by immersing the lengths of vegetable textiles in baths containing the active ingredients.

The treatment is effected on green-soutched lengths, that is to say, lengths freed from the ligneous parts of the stem. I

It would obviously be possible in theory to mix the three active ingredients, namely the alkali base, the palmitate otamine base and an oxidizing agent, for example hydrogen peroxide, in an aqueous bath and to immerse the textiles in this bath.

Only a bad result would be obtained in this way and it would be necessary to employ large quantities of reagents. If, in fact, hydrogen peroxide were directly introduced into this bath, a large part thereof would be wasted owing to the oxidation of the foreign substances which may-be eliminated for the greater part by an alkali solution containing a palmitate of amine base.

Moreover, by reason ofthe strong coloring of the .solu-.

foreign to the fibre.

The second bath contains the same ingredients as the first and, inaddition, the hydrogen peroxide, i. e. it is a finishing bath.

The concentration of the alkali base in eachof these baths may vary between 0.5% and 2% and is preferably of the order of 1%. It is generally stronger in the first bath, which is aroughing bath, and weaker, i. e. substantially half as strong, in the second, which is above all, a bath which completes the action of the first.

The concentration of the palmitate of amine base may vary between 0.05 and 5% in each of the baths. The upper limit is determined by considerations of economy and could be increased without harm.

The concentration of the hydrogen peroxide or of the substance by which it is liberated in the second bath is so adjusted that the resultant hydrogen peroxide concentration of the bath is from 0.1 to 0.4 volume.

The fibres are immersed in each of the baths for a period varying between 20 and 60 minutes. These two baths are preferably at a fairly high temperature, of the order 80 C. to 100 C.

In order to illustrate the manners in which the invention-may be carried into effect, a number of non-limitative examples of the process will be described in the following.

In the following examples, the percentage of the different ingredients of the mixture is given with reference to the weight of the water in the bath. For hydrogen peroxide, the concentration is given in volumes calculated on the total weight of the aqueous solution.

Example I Lengths of green-soutched flex are successively immersed in the two baths of the following composition:

Between the two baths, the lengths of vegetable fibres are washed in water so as to free them from the foreign substances attacked by the soda, which would colour the second bath. After the second bath, the'lengths of vegetable fibres are again washed in water, dried, flexibilised and de-gummed by the usual methods.

Example II Lengths of green-soutched hemp are successively immersed in the two baths of the following composition the two immersions being separated by an intermediate washing in water.

2nd bath:

......Water....-.-....

Potash percent 0.1 Propanolamine palmitate do 0.1 Sodium perborate do 0.5 Temperature of the bath C Period of treatment minutes" 30 The lengths of hemp are then treated as in Example I.

Example III Lengths of asclepias are successively treated in the two following baths, the treatments being separated by an intermediate washing in water.

The lengths are then treated as in Example I.

The process according to the invention gives, irrespective of'the vegetable textile fibre, a fine, strong, white tow free from oxycellulose, which fully meets the requirements of spinning and which is highly regarded by specialists. Naturally, the invention is'in' no way limited to the embodiments described which have only been referred to by way of example. i i

WhatIclaimisi i p 1. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment within first aqueous solution containing analkaline base at a concentration approximately between 0.5% to 2% and'a palmitate of a base derived from an hydrogenated compound of nitrogen, said palmitate being at a concentration approximately from 0.05% to 5%, then to a second treatment with a second aqueous solution containing the same products as the first solution and in addition a substance liberating hydrogen peroxide corresponding to 0.1to 0.4 liter of free oxygen per kg. of said second solution, said first and second treatments being eifected at a temperature approximately of 80 C. to C. for a period. of 20 to 60 minutes andsaid pahnitate being relatively stable under the conditions of treatment with said first and second solutions.

I 2. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment with a first aqueous solution containing 'an alkaline base at a concentration approximately between 0.5% to 2% and a palmitate of a base derived from an hydrogenated compound of nitrogen, said palmitate being at a concentration approximately from 0.05 to 5%, then to a washing with water, and lastly to a second treatment with a second aqueous solution containing the same products as the firstsolution and in addition a substance liberating hydrogen peroxide corresponding to 0.1 to 0.4 liter of: freeoxygen per kg. of said second solution, said first and second treatments being effected at a temperature approximately of 80? C. to 100 C. for a period of 20 .to 60 minutes and said palmitate being relatively stable uni der' the conditions oftreatment with said first and second solutions." I I v e 3. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment with a first aqueous solution containing sodium h dr ttide taiconge r tica a pr ximate y b w t.0-;5 Q 27Zi and a-palmitatgzofia base; derivedfrom' an hydrogenated compound of nitrogen, said palmitate being at a concentration approximately from 0.05% to 5%, then to a second treatment with a second aqueous solution containing the same products as the first solution and in addition a substance liberating hydrogen peroxide corresponding to 0.1 to 0.4 liter of free oxygen per kg. of said second solution, said first and second treatments being efiected at a temperature approximately of 80 C. to 100 C. for a period of to 60 minutes and said palmitate being relatively stable under the conditions of treatment with said first and second solutions.

4. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment with a first aqueous solution containing potassium hydroxide at a concentration approximately between 0.5 to 2% and a palmitate of a base derived from an hydrogenated compound of nitrogen, said palmitate being at a concentration approximately from 0.05% to 5%, then to a second treatment with a second aqueous solution containing the same products as the first solution and in addition a substance liberating hydrogen peroxide corresponding to 0.1 to 0.4 liter of free oxygen per kg. of said second solution, said first and second treatments being effected at a temperature approximately of 80 C. to 100 C. for a period of 20 to 60 minutes and said palmitate being relatively stable under the conditions of treatment with said first and second solutions.

5. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment with a first aqueous solution containing an alkaline base at a concentration approximately between 0.5% to 2% and a palmitate of propanolamine, said palmitate being at a concentration approximately from 0.05% to 5%, then to a second treatment with a second aqueous solution containing the same products as the first solution and in addition a substance liberating hydrogen peroxide corresponding to 0.1 to 0.4 liter of free oxygen per kg. of said second solution, said first and second treatments being eflected at a temperature approximately of 80 C. to 100 C. for a period of 20 to 60 minutes.

6. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment with a first aqueous solution containing an alkaline base at a concentration approximately between 0.5% to 2% and a palmitate of morpholine, said palmitate being at a concentration approximately from 0.05 to 5% then to a second treatment with a second aqueous solution containing the same products as the first solution and in addition a substance liberating hydrogen peroxide corresponding to 0.1 to 0.4 liter of free oxygen per kg. of said second solution, said first and second treatments being efiected at a temperature approximately of 80 C. to 100 C. for a period of 20 to 60 minutes.

7. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment with a first aqueous solution containing an alkaline base at a concentration approximately between 0.5% to 2% and a palmitate of tetramethylammonium, said palmitate being at a concentration approximately from 0.05% to 5%, then to a second treatment with a second aqueous solution containing the same products as the first solution and in addition a substance liberating hydrogen peroxide corresponding to 0.1 to 0.4 liter of free oxygen per kg. of said second solution, said first and second treatments being effected at a temperature approximately of 80 C. to 100 C. for a period of 20 to minutes.

8. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment with a first aqueous solution containing a sodium hydroxide at a concentration approximately between 0.5% to 2% and a palmitate of propanolamine, said palmitate being at a concentration approximately from 0.05% to 5%, then to a second treatment with a second aqueous solution containing the same products as the first solution and in addition a substance liberating hydrogen peroxide corresponding to 0.1 to 0.4 liter of free oxygen per kg. of said second solution, said first and second treatments being eflected at a temperature approximately of C. to C. for a period of 20 to 60 minutes.

9. A process for the chemical retting of lengths of vegetable textiles comprising subjecting said lengths to a first treatment with a first aqueous solution containing a potassium hydroxide at a concentration approximately between 0.5% to 2% and a palmitate of propanolamine, said palmitate being at a concentration approximately from 0.05% to 5%, then to a second treatment with a second aqueous solution containing the same products as the first solution and in addition a substance liberating hydrogen peroxide corresponding to 0.1 to 0.4 liter of free oxygen per kg. of said second solution, said first and second treatments being efiected at a temperature approximately of 80 C. to 100 C. for a period of 20 to 60 minutes.

References Cited in the file of this patent UNITED STATES PATENTS 2,048,775 Bolton July 28, 1936 2,073,682 Chesley Mar. 16, 1937 2,128,928 Estes Sept. 6, 1938 2,407,909 Vincent Sept. 17, 1946 2,530,244 Jensen Nov. 14, 1950 2,626,213 Novak Jan. 20, 1953 OTHER REFERENCES Miskel, Paper Trade J June 29, 1944, pp. 27 and 28. Ind. and Eng. Chem, January 1941, pp. 18-22. 

1. A PROCESS FOR THE CHEMICAL RETTING OF LENGTHS OF VEGETABLE TEXTILES COMPRISING SUBJECTING SAID LENGTHS TO A FIRST TREATMENT WITH A FIRST AQUEOUS SOLUTION CONTAINING AN ALKALINE BASE AT A CONCENTRATION APPORXIMATELY BETWEEN 0.5% TO 2% AND A PALMITATE OF A BASE DERIVED FROM AN HYDROGENATED COMPOUND OF NITROGEN, SAID PALMITATE BEING AT A CONCENTRATION APPROXIMATELY FROM 0.05% TO 5%, THEN TO A SECOND TREATMENT WITH A SECOND AQUEOUS SOLUTION CONTAINING THE SAME PRODUCTS AS THE FIRST SOLUTION AND IN ADDITION A SUBSTANCE LIBERATING HYDROGEN PEROXIDE CORRESPONDING TO 0.1 TO 0.4 LITER OF FREE OXYGEN PER KG. OF SAID SECOND SOLUTION, SAID FIRST AND SECOND TREATMENTS BEING EFFECTED AT A TEMPERATURE APPROXIMATELY OF 80*C. TO 100*C. FOR A PERIOD OF 20 TO 60 MINUTES AND SAID PALMITATE BEING RELATIVELY STABLE UNDER THE CONDITIONS OF TREATMENT WITH SAID FIRST AND SECOND SOLUTIONS. 